Cathodoluminescence of Feldspar Minerals
Dr. Graham Peaslee, Hope College
Sarah Brokus, Hope College
Danielle Silletti, Hope College
Dr. JoAnn Buscaglia, Counterterrorism and Forensic Science Research Unit, FBI Laboratory
A collection of North American feldspar minerals were examined using cold-cathode cathodoluminescence (CL) spectroscopy. The resulting spectra were fit and characteristic peaks were associated with each feldspar phase; these peaks are independent of geographic origin. Most of these peaks have been previously assigned to luminescent centers, such as Mn2+ and Fe3+, and structural defects. While the magnitude of these peaks depends on many co-factors, the peak centroids are shown to be consistent for replicate samples from any given location. These peak centroids are also found to vary measurably from location to location, most likely due to stoichiometric changes in the Na-K-Ca composition of the feldspars. A relationship between CL peak centroid and lattice size changes for both alkali and plagioclase feldspars has been reported previously. This novel application of an older luminescence technique yields encouraging results for the practical application of feldspar identification and provenance attribution in forensic geology.
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